1. Field of the Invention
The present invention relates to a label printing and applying machine also referred to herein as a hand labeler, and more particularly relates to a constant pressure printing mechanism for use with the hand labeler.
2. Description of the Prior Art
Known constant pressure printing mechanisms have complicated mechanisms and use many parts so that their assembly is accordingly complicated. Moreover, operation of the labeler frequently has problems, and adjustment to the constant pressure requires high skills. Examples of somewhat complicated but still effective constant pressure printing mechanisms can be found in my U.S. Pat. No. 4,149,462, issued Apr. 17, 1979 and my U.S. Pat. No. 4,113,544, issued Sept. 12, 1978.
In a hand labeler without a constant pressure printing mechanism, the density of the prints on the labels is directly dependent upon the intensity of the squeezing force applied to the hand lever of the hand labeler. If the squeezing force is too strong, the imprints are excessively dense, and if the squeezing force is too weak, the prints become excessively thin. Thus irregular quality printing occurs. Recently, regular printing has become more important because the so-called "POS (Point-of-Sales) System" has been put into practice. Highly accurate label imprints are required because the POS System resorts to optical scanner reading of the information printed on labels.
Moreover, in the POS System using bar codes, the printing area required is quite wide so that the printing pressure required is accordngly quite high.